This study of recidivism among Washington supermax prisoners used a retrospective matched control design, matching supermax prisoners one-to-one with nonsupermax prisoners on mental illness status and up to eight recidivism predictors. Supermax prisoners committed new felonies at a higher rate than nonsupermax controls, but the difference was not statistically significant. Prisoners released directly from supermax to the community, however, showed significantly higher felony recidivism rates than their nonsupermax controls and committed new offenses sooner than supermax prisoners who left supermax 3 months or more before prison release. Limitations, methodological issues, and policy implications are considered. (Contains 5 tables and 7 notes.)